Plasma Technology  

Cryo deep Si etching:
20 um diameter holes etched 64 um
using 20 nm alumina etch mask.
The mask is still present.

Bosch deep Si etching with
Alumina mask
45 nm and 88 nm diameter silicon P+N
and P+ pillars. Probe is a tungsten probe tip.
Probe stage is mounted in an FEI Quanta.

Cryo deep Si etching:
Gallium implanted etch mask
10 um square etched to a
depth of 10.5 um

Bosch deep Si etching with
Ga implanted mask
680 nm silicon etch, depth over a range
of squares in 50 nm increments starting at 500 nm

Plasmalab System 100
with ICP Source and loadlock

ICP technology


Deep Si Etching using a Ga implanted and a Al2O3 mask


Gallium implanted at a 45 degree angle
on a 50 um diameter silicon pillar
etched 60 um tall

The Al2O3 mask was deposited by reactive magnetron
sputtering, the pattern is defined by lift off technology.

The Ga has been implanted by FIB:
Dose ~ 2*1016 cm-2
Ga doping of ~ 6*1021 cm-3
Implant depth ~ 35 nm +/- 12.5 nm ->
total mask thickness is 25 nm

Sputtered Alumina Etch Masks give a high selectivity
and are easy to remove with BHF or NH4OH (RCA -1 clean).
Gallium FIB Implanted Etch Mask show good selectivity,
are easy to patter, 3-D patterning is still under investigation.

This results have been obtained at
the Hertz Foundation
M. David Henry, Axel Scherer, Michael Shearn

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